I've rarely had any issues with the ABS on our 1100A.
Over thirteen years the warning light has come on a few times.
First thing to do when you get a warning light is just stop; turn the bike off and restart. ABS computer will do another self test as normal. Move off again and if all is well the lights should go off.
If it stays on then it's still no drama as you'll just revert back to non ABS but when you get back home do a check of the ABS sensors and the rings to make sure there is no dirt or grease which can cause a warning. Then check the wiring from the sensors to make sure that's ok.
Another possibility is that the front sensor maybe loose. It needs to be removed before the wheel can be removed. Was it mounted back in place and tightened because if not the sensor to ring gap will be wrong and cause a warning as well.
That's all the simple stuff and anything else would be major and related to maybe the ABS computer or the front and rear modulators.